Travel Planning
Chamorro Standard Time (UTC+10) — no daylight saving, ever
Verified 2026 · Island Seeker Editorial
quick answer
Guam is on Chamorro Standard Time (ChST), UTC+10, year-round — it does not observe daylight saving time. That puts Guam 1 hour ahead of Tokyo and Seoul, 2 hours ahead of Manila, and roughly 14–15 hours ahead of the US East Coast (14 during Eastern Daylight Time, 15 during Eastern Standard Time). Guam's tourism board brands it "Where America's Day Begins" because it's the first US territory to see each new day.
Time zone
Chamorro Standard Time (ChST), UTC+10
vs. Tokyo / Seoul
Guam is 1 hour ahead
vs. Manila
Guam is 2 hours ahead
Daylight saving
None — Guam never changes clocks
Guam uses Chamorro Standard Time (ChST), which is a fixed UTC+10 offset year-round. Unlike the US mainland, Guam does not observe daylight saving time, so the offset from any given city can shift by an hour depending on whether that city is currently on standard or daylight time.
Because Guam sits just west of the International Date Line, it's one of the first places in the US to greet each new day — the basis for Guam's official tourism slogan, "Where America's Day Begins."
Tokyo and Seoul (JST/KST, UTC+9): Guam is 1 hour ahead. Noon in Guam is 11am in Tokyo or Seoul.
Manila (UTC+8): Guam is 2 hours ahead. Noon in Guam is 10am in Manila.
Sydney (AEST UTC+10, or AEDT UTC+11 during Australian daylight saving, roughly October–April): Guam is level with Sydney on standard time, or 1 hour behind during Sydney's daylight saving.
Los Angeles (PDT UTC-7 / PST UTC-8): Guam is 17 hours ahead during Pacific Daylight Time, 18 hours ahead during Pacific Standard Time.
New York (EDT UTC-4 / EST UTC-5): Guam is 14 hours ahead during Eastern Daylight Time, 15 hours ahead during Eastern Standard Time.
Because of the International Date Line, Guam is technically a full calendar day ahead of the US mainland — when it's 6pm Monday in Guam, it's already Sunday evening in Los Angeles or New York.
Visitors from Japan and Korea barely notice jet lag — the 1-hour difference is trivial. Visitors from the US mainland cross the International Date Line and face the largest possible time shift (14–18 hours), which often feels easier to adjust to than a same-day shift of similar size, since you effectively skip or repeat a day rather than fight your body clock hour by hour.
A simple rule for mainland US travellers: try to sleep on the outbound flight if it lands in Guam's morning or afternoon, and get outside in daylight as soon as you land to reset your internal clock faster.
questions & answers
What time zone is Guam in?
Guam is in Chamorro Standard Time (ChST), a fixed UTC+10 offset. Guam does not observe daylight saving time, so it stays on UTC+10 all year.
Does Guam have daylight saving time?
No. Guam stays on Chamorro Standard Time (UTC+10) year-round and never adjusts its clocks, unlike the US mainland.
How many hours ahead is Guam of Tokyo and Seoul?
Guam is 1 hour ahead of Tokyo and Seoul, since both cities use Japan Standard Time / Korea Standard Time (UTC+9) year-round with no daylight saving.
How many hours ahead is Guam of the US mainland?
Guam is roughly 14–18 hours ahead of the US mainland, depending on the city and whether it's on daylight saving time. For example, Guam is 14 hours ahead of New York during Eastern Daylight Time and 18 hours ahead of Los Angeles during Pacific Standard Time. Because Guam is on the other side of the International Date Line, it's also a full calendar day ahead.
Why is Guam called 'Where America's Day Begins'?
Guam sits just west of the International Date Line, making it one of the first places under the US flag to see each new day — the origin of Guam's official tourism slogan.
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